An assay using localized surface plasmon resonance and gold nanorods functionalized with aptamers to sense the cytochrome-c released from apoptotic cancer cells for anti-cancer drug effect determination

Abstract

To determine The degree of cancer cell killing after treatment with chemotherapeutic drugs, we have developed A sensitive platform using localized surface plasmon resonance (LSPR) and aptamers to detect The extracellular cytochrome-c (cyto-c), A mitochondrial protein released from cancer cells for The induction of apoptosis after treatment, to evaluate The effectiveness of cancer therapy. In this assay, A short single-stranded 76-mer DNA aptamer with A unique DNA sequence, which binds towards The cyto-c like an antibody with A high binding affinity and specificity, was conjugated to gold nanorods (AuNR) for LSPR sensing. Practically, cyto-c was first grabbed by A capturing antibody functionalized on The surface of micro-magnetic particles (MMPs). Subsequently, The AuNR-conjugated aptamer was added to form A complex sandwich structure with cyto-c (i.e., (MMP-Ab)-(cyto-c)-(AuNR-aptamer)) after washing away The non-target impurities, such as serum residues and intracellular contents, in A microfluidic chip. The sandwich complex led to formation of AuNR aggregates, which changed The LSPR signals in relation to The amount of cyto-c. With The LSPR signal enhancement effects from The AuNRs, The detection limit of cyto-c, sparked in human serum or culture medium, was found to be 0.1 ng/mL in our platform and the whole sensing process could be completed within two hours. Moreover, we have applied this assay to monitor The apoptosis in leukemia cancer cells induced by A potential anti-cancer agent phenylarsine oxide.